(Hirta) (UK) ID N° 387 Bis Background Note: St. Kilda
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WORLD HERITAGE NOMINATION – IUCN TECHNICAL EVALUATION Saint Kilda (Hirta) (UK) ID N° 387 Bis Background note: St. Kilda was inscribed on the World Heritage List in 1986 under natural criteria (iii) and (iv). At the time IUCN noted that: The scenery of the St. Kilda archipelago is particularly superlative and has resulted from its volcanic origin followed by weathering and glaciation to produce a dramatic island landscape. The precipitous cliffs and sea stacks as well as its underwater scenery are concentrated in a compact group that is singularly unique. St. Kilda is one of the major sites in the North Atlantic and Europe for sea birds with over one million birds using the Island. It is particularly important for gannets, puffins and fulmars. The maritime grassland turf and the underwater habitats are also significant and an integral element of the total island setting. The feral Soay sheep are also an interesting rare breed of potential genetic resource significance. IUCN also noted: The importance of the marine element and the possibility of considering marine reserve status for the immediate feeding areas should be brought to the attention of the Government of the UK. The State Party presented a re-nomination in 2003 to: a) seek inclusion on the World Heritage List for additional natural criteria (i) and (ii), as well as cultural criteria (iii), (iv), and (v), thus re-nominating St. Kilda as a mixed site; and b) to extend the boundaries to include the marine area. _________________________________________________________________________ 1. DOCUMENTATION i) IUCN/WCMC Data Sheet: 25 references. ii) Additional Literature Consulted: Stattersfield. A.J. et al.,1998, Endemic Bird Areas of the World: Priorities for Biodiversity Conservation. Birdlife International, Cambridge, U.K; UNESCO, 2003, Draft UNESCO World Heritage Marine Strategy; S. Palumbi, 2003, Marine Reserves – A tool for ecosystem management conservation, Pew Oceans Commission; MPA News related to spatial MPA design for marine ecosystems: (Vol4#6 Channel Islands lessons; Vol5#4 High Seas Targets; Vol5#6 Fisheries yields in reserve design; Vol5#3 Open Ocean MPAs); OSPAR Quality Status Report 2000 – Celtic Seas; JNCC Dec. 2003 website (www.jncc.gov.uk/marine/), DEFR, 2000, Deep Water Demersal Fisheries; Scottish Coastal Forum, 2003, A Strategy for Scotland’s Coasts and Inshore Waters - Tourism and Recreation Task Group; Discussion Paper by the Scottish Executive, 2003, The Sustainable Development of Scotland’s Marine Resources: Towards New Management Framework Options?, CORDAH Ltd.; St. Kilda World Heritage Site Risk Assessment, 2003, for the Scottish Executive. iii) Consultations: 4 External reviewers. iv) Field Visit: J. Thorsell, June 1986. 155 2. SUMMARY OF NATURAL VALUES The St. Kilda Archipelago (SKA) is a remote Atlantic island group lying 64 km west of the Outer Hebrides off the west coast of Scotland. Currently, the St. Kilda World Heritage site (IUCN Category IV Protected Area) includes the terrestrial area of the archipelago totaling 854.6 ha above the Mean High Water Spring Mark, with four islands (Hirta, Boreray, Soay and Dun) and numerous sea stacks (the three largest being Levenish, Stac an Armin and Stac Lee). This re-nomination proposes to extend the boundary into the marine area surrounding SKA, thus including an additional 23,346.8 ha, from the Mean High Water Spring Mark out to the boundary. The total area of the proposed site is therefore 24,201.4ha, an increase of 96% to the World Heritage site. No buffer zone is proposed. From an oceanographic and geomorphologic perspective, SKA is near the western margin of the Hebrides Shelf, and further west is located the Rockall Basin. SKA is considered an oceanic North East Atlantic archipelago in the Palaearctic realm. It reveals a rich fabric of interlinked natural features that reflect the 50-60 million years of geological history. The oceanic islands character of SKA creates many complex and different ecological niches given the combination of steep rock formations, wave exposure, water depth, water clarity, isolation and limited disturbance that have resulted in a highly specialized marine and terrestrial biodiversity. The marine biodiversity is associated to three key zones: (a) the intertidal (high-low water) or ‘eulittoral’ marine zone, generally 5 metres between mean high and low tides, is highly variable with wave and tide changes and is dominated by limpets, barnacles, mussels and fucoid algae; (b) the infralittoral zone are between – 5m > 60 m, and are dominated by kelp beds, very thick in the upper areas, but spreading to a ‘forest or park’ further down with less light. Some of the more ‘intertidal’ kelps extend into the beginnings of this zone due to the high water clarity that occurs in SKA, and; (c) the Sublittoral or Circalittoral zone extends down from about – 60 m to – 80 m and spreads out to the continental shelf. Encrusting animals dominate this zone, including scavenging and grazing sea slugs, gastropods, crabs and echinoderms. As for many islands, the terrestrial fauna and flora show low species diversity but the islands have large breeding populations of seabirds. The flora, impoverished due to the small size of the islands, nonetheless presents 184 species of ferns, flowers and grasses and 170 species of funghi. St. Kilda is, however, rich in some lower plants with 194 species of lichen and 160 species of bryophyte. The SKA is Europe’s most significant seabird colony and major seabird breeding station in the NE Atlantic. During the summer months the SKA is home to over a million seabirds, including 700,000 breeding pairs. The four main islands and associated sea stacks and rocky cliffs provide a rich diversity of breeding habitat. Oceanic vegetation on the islands provides nesting materials. The island of Boreray and its ‘sea stacks’ support the world’s largest colony of gannets, and one of the largest colony of northern fulmars. It is also the most important breeding station of Leach’s storm-petrol in the NE Atlantic. The key species in the SKA include: northern fulmar, manx shearwater, European storm-petrol, leach’s storm petrol, northern gannet, European shag, arctic skua, great skua, mew gull, lesser black-backed gull, herring gull, great-black backed gull, black-legged kittiwake, common guillemot, razor bill, black guillemot, atlantic puffin. Ten species of cetaceans have been sighted with minke and killer whales, harbour porpoises, Risso’s dolphins, Atlantic white-sided dolphin and white-beaked dolphin as regular visitors. Between 300 and 400 Atlantic Grey seals are present at the SKA throughout the year, with approximately 50 breeding pups due to limited haul out sites. 3. COMPARISONS WITH OTHER AREAS In relation to criteria (i) on geological considerations, the re-nomination claims global importance significance for the St Kilda site on the basis of the significance of on-going geological processes and significant geomorphic or physiographic features. More specifically, the claim for outstanding universal value is focused on coastal and submarine geomorphology. It is noted that the primary geological significance of the St Kilda archipelago in a global context is that it is an eroded remnant of an ancient (Palaeocene) volcanic massif. However the great majority of the world’s oceanic islands (including several World Heritage sites) are eroded volcanoes of one form or another. St Kilda is neither unique nor exceptional in relation to this aspect. The re-nomination document claims that the archipelago exhibits “a complex terrestrial landscape extending uninterrupted into the submarine zone” and that “such a combined terrestrial and marine landscape in an island setting is unique in the Palaearctic Realm.” This is questioned, since on all islands (and all continents) the terrestrial landscape extends in an uninterrupted manner below sea level. A case is also made for the exceptional coastal landforms, including “the most spectacular cliff scenery in Great Britain” – but these attributes are already recognised in World Heritage terms by the property’s inscription under criterion 44(a)(iii). In the marine zone, the two conspicuous submerged former coastlines and associated landforms, subsequently “drowned” by post-glacial rise in sea level, are noted as exceptional in the nomination document. In fact, this phenomenon is commonplace and globally ubiquitous around islands and continents. The seabed sediments are highlighted (and were re-mapped for the nomination), but no attempt is made to relate their contribution to outstanding geological value – and they are referred to as having regional significance only. On land, the evidence of Pleistocene glaciation and associated landforms, and the periglacial deposits are unexceptional in global terms, including on islands. Macquarie I., Heard & McDonald I. and the NZ Subantarctic Islands are among the existing World Heritage island sites that display classical and widespread glacial and periglacial processes and forms (despite the NZ islands not being listed for their geological values). In relation to biodiversity values there is only one other island site with marine features in the ‘Palaearctic Realm’ - the complex of Cape Girolata-Cape Porto, Scandola Nature Reserve in Corsican France. However it is typical marine fauna of the Mediterranean, which is extremely different from that of the North Atlantic for a range of climatic, ocean and geographic reasons. This Corsican site is only 12,000 ha total, of which only 4,200 ha is marine, in comparison to the ~24,000 marine hectares proposed for the nominated site. The rest of the island-marine site complexes that have any ecological similarity to SKA are in the southern hemisphere – one in the ‘Australian Realm’ (Lord Howe Island); two in the Antarctic realm (e.g. Heard and McDonald Islands in Australia, New Zealand Sub-Antarctic Islands in NZ and the Gough Island Wildlife Reserve on Tristan de Cuna in the South Atlantic under UK jurisdiction) and three in the Neotropical Realm (Fernando de Noronha/Atol das Roca in Brazil, Cocos Island in Costa Rica and the Galapagos in Ecuador.) Hence the SKA site is unique in the Northern Hemisphere from a WH perspective.